The theory of the marketing firm locates the rationale of the modern business enterprise in its responding profitably to the imperatives of marketing-orientation. Economic theories of the firm generally fail to recognise these imperatives, enhanced consumer choice and sophistication, which entail marketing-orientation as the rationale of the firm. The chapter proposes a competence theory of the firm as a metacontingency and examines the bilateral contingencies by which firms link to their consumerates, which indicate their capacities for customer-orientation. The marketing firm emerges as a means of encapsulating entrepreneurship, economising on transaction costs, and enabling the management of marketing specialisation.